Summary of Significant Accounting Policies - Summary of Impact to Statements of Net Loss and Comprehensive Loss (Detail) - USD ($) $ in Thousands	3 Months Ended						9 Months Ended
	Sep. 30, 2020	Jun. 30, 2020	Mar. 31, 2020	Sep. 30, 2019	Jun. 30, 2019	Mar. 31, 2019	Sep. 30, 2020	Sep. 30, 2019
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Net (loss) income	$ (2,316)	$ (81,687)	$ (184,123)	$ (36,351)	$ (36,301)	$ (29,369)	$ (268,124)	$ (102,021)
Other comprehensive (loss) income	$ 2,458	$ 7,219	$ (16,707)	(4,852)	$ 2,974	$ (456)	$ (7,030)	(2,334)
Unadjusted [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Net (loss) income				(35,678)				(101,032)
Other comprehensive (loss) income				(5,164)				(2,069)
Impact of Adoption [Member] | ASU 2016-01 [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Net (loss) income				(312)				265
Other comprehensive (loss) income				312				(265)
Impact of Adoption [Member] | ASC 842 [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Net (loss) income				(32)				(157)
Impact of Adoption [Member] | ASU 2018-07 [Member]
New Accounting Pronouncements Or Change In Accounting Principle [Line Items]
Net (loss) income				$ (329)				$ (1,097)